Magnetic resonance signal acquisition method, apparatus, magnetic resonance scanning system, and storage medium
By adjusting the excitation timing of the radio frequency pulses, when the number of groups of multiple layers being excited simultaneously is even, spatially adjacent layers are not temporally adjacent. This solves the problem of reduced signal-to-noise ratio caused by interlayer crosstalk in the multilayer simultaneous excitation method, and improves the signal quality and imaging effect of magnetic resonance imaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- UNITED IMAGING RES INST OF INTELLIGENT IMAGING
- Filing Date
- 2022-12-28
- Publication Date
- 2026-05-29
Smart Images
Figure CN115902732B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of magnetic resonance technology, and in particular to a magnetic resonance signal acquisition method, apparatus, magnetic resonance scanning system and storage medium. Background Technology
[0002] With the development of magnetic resonance imaging (MRI) technology, multi-slice simultaneous excitation (MSE) technology has emerged. MSE is an accelerated MRI technique that can acquire signals from multiple slices simultaneously in a single excitation, thereby significantly reducing scan time and increasing imaging speed. In MRI, the slice profile of the slice-selective radiofrequency pulse is not an ideal rectangle, but rather has a transition region with adjacent slices. Exciting a particular slice can cause signal saturation in the transition region of adjacent slices, leading to a decrease in the acquired signal and a lower signal-to-noise ratio.
[0003] Current multi-layer simultaneous excitation methods or traditional methods suffer from problems such as poor imaging results. Summary of the Invention
[0004] Therefore, it is necessary to provide a magnetic resonance signal acquisition method, device, magnetic resonance scanning system, computer-readable storage medium, and computer program product that can improve the imaging effect in response to the above-mentioned technical problems.
[0005] Firstly, this application provides a method for acquiring magnetic resonance signals. The method includes:
[0006] Obtain the number of groups of radio frequency pulses that simultaneously excite multiple layers of the target object;
[0007] When the number of groups of multiple layers simultaneously excited is even, the preset excitation timing is adjusted for the target group of layers to obtain the target excitation timing; the target group of layers includes the first or last group of layers excited within one repetition time of the radio frequency pulse; in the target excitation timing, spatially adjacent layers are not temporally adjacent.
[0008] Based on the target excitation timing control, the radio frequency pulse is used to perform multi-layer simultaneous excitation processing on the target object;
[0009] Multi-layer simultaneous excitation data of the target object are collected; the multi-layer simultaneous excitation data is used to perform magnetic resonance imaging on the target object.
[0010] In one embodiment, the step of obtaining the number of groups of radio frequency pulses simultaneously exciting multiple layers of the target object includes:
[0011] Obtain the scanning parameters of the target object; the scanning parameters include the number of layers simultaneously excited by the radio frequency pulse and the total number of layers of the target object;
[0012] The number of groups of simultaneous multi-layer excitation is determined based on the number of simultaneously excited layers and the total number of layers.
[0013] In one embodiment, for a preset excitation sequence, within a repetition time period, the timing of each layer with odd-numbered numbers precedes the timing of each layer with even-numbered numbers, or the timing of each layer with odd-numbered numbers follows the timing of each layer with even-numbered numbers; the numbering is obtained by sequentially sorting the spatial positions of each layer of the target object; the numerical difference between the numbers of the layers simultaneously excited in the preset excitation sequence is an integer multiple of the number of groups of multiple layers simultaneously excited.
[0014] In one embodiment, when the number of simultaneously excited multilayer groups is even, the step of adjusting the preset excitation timing for the target layer group to obtain the target excitation timing includes:
[0015] Based on the number of groups of simultaneous excitation of the multilayers, several target layer groups are determined; the target layer group includes layers with the same temporal sequence that are simultaneously excited.
[0016] For the preset excitation timing sequence, the timing sequence of each target layer group is adjusted to obtain the target excitation timing sequence; the timing adjustment position of the target layer group is determined based on the timing sequence of the target layer group in the preset excitation timing sequence.
[0017] In one embodiment, the step of adjusting the timing of each target layer group to obtain the target excitation timing for the preset excitation timing includes:
[0018] Based on the preset excitation timing sequence, and according to the preset timing adjustment order, the timing sequence of each target layer group is adjusted according to the timing adjustment position to obtain the target excitation timing sequence; in the preset timing adjustment order, the timing adjustment positions of each target layer group are different, and the timing adjustment positions of each target layer group are all less than a preset value; the preset value is a value determined based on the number of groups of multiple layers being excited simultaneously.
[0019] In one embodiment, the method further includes:
[0020] When the number of groups of the multi-layer simultaneous excitation is odd, the radio frequency pulse is controlled based on the preset excitation timing to perform the multi-layer simultaneous excitation process on the target object.
[0021] Secondly, this application provides a magnetic resonance signal acquisition device. The device includes:
[0022] The group number acquisition module is used to acquire the number of groups of radio frequency pulses that simultaneously excite multiple layers of the target object;
[0023] The timing adjustment module is used to adjust the preset excitation timing for the target layer group when the number of groups of the multilayers being excited simultaneously is even, so as to obtain the target excitation timing; the target layer group includes the first or last group of layers excited within one repetition time of the radio frequency pulse; in the target excitation timing, spatially adjacent layers are not temporally adjacent.
[0024] The first excitation module is used to control the radio frequency pulse based on the target excitation timing to perform multi-layer simultaneous excitation processing on the target object;
[0025] The target imaging module is used to acquire multi-layer simultaneous excitation data of the target object; the multi-layer simultaneous excitation data is used to perform magnetic resonance imaging on the target object.
[0026] Thirdly, this application provides a magnetic resonance scanning system. The system includes a magnetic resonance scanning device and a processing unit connected to the magnetic resonance scanning device; the magnetic resonance scanning device is used to transmit radio frequency pulses to the target object to perform the multi-layer simultaneous excitation processing, and to acquire the multi-layer simultaneous excitation data of the target object; the processing unit stores a computer program, and when the processing unit executes the computer program, it implements the steps of the above-described method.
[0027] Fourthly, this application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program thereon, which, when executed by a processor, implements the steps of the above-described method.
[0028] Fifthly, this application provides a computer program product. The computer program product includes a computer program that, when executed by a processor, implements the steps of the method described above.
[0029] The aforementioned magnetic resonance signal acquisition method, apparatus, magnetic resonance scanning system, computer-readable storage medium, and computer program product, the method acquires the number of groups of simultaneous multi-layer excitation of a target object using radio frequency pulses; when the number of groups of simultaneous multi-layer excitation is even, a preset excitation timing sequence is adjusted for the target layer groups, thereby ensuring that the obtained target excitation timing sequence satisfies that temporally adjacent layers are not spatially adjacent, thus reducing inter-layer crosstalk; the radio frequency pulses are controlled based on the target excitation timing sequence to perform multi-layer simultaneous excitation processing on the target object; multi-layer simultaneous excitation data for magnetic resonance imaging of the target object are acquired, improving the quality and signal-to-noise ratio of the acquired signal, thereby improving the final magnetic resonance imaging effect. Attached Figure Description
[0030] Figure 1 This is a flowchart illustrating a magnetic resonance signal acquisition method in one embodiment;
[0031] Figure 2This is a schematic diagram of a preset excitation timing for an example;
[0032] Figure 3 This is a flowchart illustrating the magnetic resonance signal acquisition steps in one embodiment;
[0033] Figure 4 This is a flowchart illustrating the magnetic resonance signal acquisition steps in another embodiment;
[0034] Figure 5 This is a schematic diagram of the target firing timing in an example;
[0035] Figure 6 This is a structural block diagram of a magnetic resonance signal acquisition device in one embodiment;
[0036] Figure 7 This is an internal structural diagram of the processing unit in one embodiment. Detailed Implementation
[0037] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.
[0038] It should be noted that multi-layer simultaneous excitation is a magnetic resonance imaging acceleration technique that can acquire signals from multiple layers simultaneously in a single excitation, thereby significantly reducing scan time and increasing imaging speed.
[0039] In magnetic resonance imaging (MRI), the slice profile of the selected radio frequency pulse is not an ideal rectangle, but rather has a transition region with adjacent slices. Exciting a slice can cause signal saturation in the transition region of adjacent slices, leading to a decrease in the acquired signal and signal-to-noise ratio (SNR). This phenomenon is called inter-slice crosstalk (ISC). To reduce ISC, sufficient longitudinal relaxation recovery time needs to be allowed for the saturated transition region. In multi-slice imaging, reducing ISC typically employs an alternating excitation method for odd and even slices. However, this method is not suitable for simultaneous multi-slice excitation imaging in some cases. This application proposes a magnetic resonance signal acquisition method, apparatus, magnetic resonance scanning system, computer-readable storage medium, and computer program product for multi-slice imaging with simultaneous excitation, which can optimize the slice excitation sequence and minimize ISC in simultaneous multi-slice excitation imaging.
[0040] In one embodiment, such as Figure 1 As shown, a method for acquiring magnetic resonance signals is provided. The method includes:
[0041] Step 110: Obtain the number of groups of radio frequency pulses that simultaneously excite multiple layers of the target object;
[0042] Specifically, the Simultaneous Multi-Slice (SMS) scanning technique can be used to simultaneously excite multiple layers of the target object using radio frequency pulses. For example, a group of layers can be excited at a time, where each group of layers includes at least two layers that are not adjacent in spatial location, and the corresponding magnetic resonance signals are acquired, thereby improving the scanning speed of magnetic resonance.
[0043] It should be noted that current methods for optimizing the excitation sequence in single-band multi-layer imaging can be employed. For example, alternating excitation and acquisition of odd and even layers can reduce inter-layer crosstalk in multi-layer imaging. Within a relatively long repetition time (TR), layers with odd-numbered spatial locations can be excited first in a specific layer group order, simultaneously acquiring the corresponding magnetic resonance signals. Then, layers with even-numbered spatial locations can be excited in a specific layer group order, simultaneously acquiring the corresponding magnetic resonance signals. Alternatively, layers with even-numbered spatial locations can be excited first, followed by layers with odd-numbered spatial locations, until all layers are excited, acquiring the corresponding magnetic resonance signals simultaneously. The layer numbers can be obtained by sequentially sorting the spatial locations of the imaging layers based on the target object. The excitation timing of each layer is identical within each repetition time. Using these methods, the scanning speed of magnetic resonance imaging can be increased while allowing approximately TR / 2 of the longitudinal relaxation recovery time in the transition region between adjacent layers in spatial location.
[0044] Furthermore, the number of groups of simultaneous multi-layer excitations can be the number of times the radio frequency pulses simultaneously excite the target object within a repetition time TR. By obtaining the number of groups of simultaneous multi-layer excitations, the timing of simultaneous multi-layer excitations of the target object can be adjusted in a targeted manner to reduce inter-layer crosstalk.
[0045] In some examples, such as Figure 2The diagram illustrates the use of the above-mentioned odd-even layer staggered excitation acquisition method. The horizontal axis t represents the time dimension, and the vertical axis d represents the spatial dimension. The total number of imaging layers for the target object is 24. A single radio frequency pulse can simultaneously excite two layers for the target object, resulting in 12 groups of layers being simultaneously excited within one repetition time TR (e.g., repetition time TR1). For two adjacent repetition times TR, such as TR1 and TR2, the last group of layers excited within TR1 includes layers 12 and 24, while the first group of layers excited within TR2 includes layers 1 and 13. Layers 12 and 13 are not only temporally adjacent but also spatially adjacent, leading to a more significant signal saturation effect between the two repetition times TR. This will cause significant interlayer crosstalk, manifesting as a significantly lower acquisition signal strength for layer 13 compared to other layers. Therefore, it is necessary to adjust the temporal sequence of simultaneous multilayer excitation for the target object to avoid temporally adjacent layers also being spatially adjacent, thereby reducing interlayer crosstalk.
[0046] Step 120: When the number of groups of multiple layers being excited simultaneously is even, the preset excitation timing is adjusted for the target layer group to obtain the target excitation timing; the target layer group includes the first or last group of layers excited within one repetition time of the radio frequency pulse; in the target excitation timing, spatially adjacent layers are not temporally adjacent.
[0047] Specifically, the above-mentioned method of alternating excitation and acquisition of odd and even layers is not suitable for multi-layer imaging with simultaneous excitation of multiple layers in some cases. For example, when the number of groups of multiple layers being excited simultaneously is even, for two adjacent repetition times (TR), some layers in the last excited layer group in the previous repetition time TR and the first excited layer group in the next repetition time TR are spatially adjacent. As a result, layers that are adjacent in both time and space have a more significant signal saturation effect between two repetition times (TR), causing obvious inter-layer crosstalk, which will lead to a significant reduction in the magnetic resonance acquisition signal for these layers and affect the quality of magnetic resonance imaging. The preset excitation timing can be the excitation timing under the current odd-even layer interleaved excitation acquisition method for the target object. When the number of groups of multiple layers excited simultaneously is even, the preset excitation timing can be adjusted for the target layer group. The position of the first or last group of layers excited within one repetition time of the radio frequency pulse is adjusted in the preset excitation timing to obtain the target excitation timing. By adjusting the timing of the target layer group, the timing of the last group of layers excited within one repetition time of the radio frequency pulse in the preset excitation timing and the timing of the first group of layers excited within the next repetition time are not adjacent in the target excitation timing. This satisfies the requirement that spatially adjacent layers are not adjacent in the timing of the target excitation timing, thereby reducing interlayer crosstalk.
[0048] In some examples, such as Figure 2 As shown, the preset excitation timing can be to excite the following layer groups sequentially within a repetition time: layer group including layer 1 and layer 13, layer group including layer 3 and layer 15, layer group including layer 5 and layer 17, layer group including layer 7 and layer 19, layer group including layer 9 and layer 21, layer group including layer 11 and layer 23, layer group including layer 2 and layer 14, layer group including layer 4 and layer 16, layer group including layer 6 and layer 18, layer group including layer 8 and layer 20, layer group including layer 10 and layer 22, and layer group including layer 12 and layer 24. To ensure that layer 12 excited within repetition time TR1 and layer 13 excited within repetition time TR2 are not adjacent, the timing of the layer group including layer 12 and layer 24 in the preset excitation timing sequence can be adjusted, or the timing of the layer group including layer 1 and layer 13 in the preset excitation timing sequence can be adjusted. In the resulting target excitation timing sequence, layer 12 and layer 13 are no longer adjacent in timing, thereby reducing the interlayer crosstalk generated between layer 12 and layer 13 in the traditional method.
[0049] Step 130: Based on the target excitation timing control radio frequency pulse, perform multi-layer simultaneous excitation processing on the target object;
[0050] Specifically, the radio frequency pulse can be controlled based on the target excitation timing obtained by adjusting the preset excitation timing, and then the target object can be subjected to multi-layer simultaneous excitation processing according to the target excitation timing to obtain the magnetic resonance signals of each imaging layer of the target object. By performing multi-layer simultaneous excitation processing on the target object based on the target excitation timing, the inter-layer crosstalk problem caused by multi-layer simultaneous excitation of the target object with the preset excitation timing can be avoided.
[0051] Step 140: Acquire multi-layer simultaneous excitation data of the target object; the multi-layer simultaneous excitation data is used to perform magnetic resonance imaging on the target object.
[0052] Specifically, multi-layer simultaneous excitation data of the target object can be acquired. This multi-layer simultaneous excitation data can include magnetic resonance signals from various imaging layers of the target object, and can be used for magnetic resonance imaging of the target object. By acquiring multi-layer simultaneous excitation data of the target object and performing magnetic resonance imaging, the imaging effect of the target object can be improved.
[0053] In this embodiment, the number of groups of simultaneous excitation of multiple layers of the target object by radio frequency pulses is obtained; when the number of groups of simultaneous excitation of multiple layers is even, the preset excitation timing is adjusted for the target layer group, so that the obtained target excitation timing satisfies that the temporally adjacent layers are not spatially adjacent, thereby reducing interlayer crosstalk; the radio frequency pulses are controlled based on the target excitation timing to perform multi-layer simultaneous excitation processing on the target object; multi-layer simultaneous excitation data for magnetic resonance imaging of the target object are collected, which improves the quality and signal-to-noise ratio of the collected signal, thereby improving the final magnetic resonance imaging effect.
[0054] In one embodiment, such as Figure 3 As shown, the steps for obtaining the number of groups of radio frequency pulses simultaneously exciting multiple layers of a target object include:
[0055] Step 310: Obtain the scanning parameters of the target object; the scanning parameters include the number of layers simultaneously excited by the radio frequency pulses and the total number of layers of the target object;
[0056] Step 320: Determine the number of groups of multiple layers to be simultaneously excited based on the number of layers being excited simultaneously and the total number of layers.
[0057] Specifically, the number of layers simultaneously excited by the radio frequency pulse and the total number of layers of the target object can be set according to the scanning imaging requirements of the target object. For the target object, a single radio frequency pulse can simultaneously excite MB layers. The number of groups of multiple layers simultaneously excited can be obtained based on the total number of layers Ns and the number of layers MB simultaneously excited. For example, the number of groups of multiple layers simultaneously excited can be the value of the total number of layers Ns divided by the number of layers MB simultaneously excited. Scanning parameters can be flexibly set, thereby maintaining the signal-to-noise ratio and contrast of the acquired magnetic resonance signals generated into the image without extending the scan time.
[0058] In some examples, when the total number of imaging layers Ns divided by the number of simultaneously excited layers MB is not an integer, the total number of imaging layers Ns divided by the number of simultaneously excited layers MB can be rounded to obtain the number of groups of multiple simultaneous excitations.
[0059] In one embodiment, for a preset excitation timing sequence, within a repetition time, the timing sequence of each layer with odd numbers is before the timing sequence of each layer with even numbers, or the timing sequence of each layer with odd numbers is after the timing sequence of each layer with even numbers; the numbers are obtained by sequentially sorting the spatial positions of each layer based on the target object; the numerical difference between the numbers of the layers simultaneously excited in the preset excitation timing sequence is an integer multiple of the number of groups of multiple layers simultaneously excited.
[0060] Specifically, the layers of the target object can be sequentially numbered based on their spatial location in the imaging sequence to determine their individual numbers. For the preset excitation timing, within a single repetition time, the radio frequency pulse can excite the odd-numbered layers first, followed by the even-numbered layers; conversely, the radio frequency pulse can excite the even-numbered layers first, followed by the odd-numbered layers; again, the odd-numbered layers are always after the even-numbered layers. The simultaneously excited layers have the same timing within the preset excitation timing, and the numerical difference between the numbers of the simultaneously excited layers can be an integer multiple of the number of layers to be simultaneously excited, ensuring that the simultaneously excited layers are spatially separated. By using the aforementioned preset excitation timing sequence, the excitation order of each imaging layer of the target object can be initially sorted, which facilitates targeted adjustment of the excitation timing sequence of each imaging layer of the target object and avoids interlayer crosstalk problems caused by multi-layer simultaneous excitation processing based on the preset excitation timing sequence.
[0061] In some examples, such as Figure 2 As shown, in each layer group that is excited simultaneously, the numerical difference between the layer numbers is 12, which is an integer multiple of the number of layers excited simultaneously, 12. The preset excitation sequence may include, within a repeating time, sequentially exciting the following layer groups: layer group including layer 1 and layer 13, layer group including layer 3 and layer 15, layer group including layer 5 and layer 17, layer group including layer 7 and layer 19, layer group including layer 9 and layer 21, layer group including layer 11 and layer 23, layer group including layer 2 and layer 14, layer group including layer 4 and layer 16, layer group including layer 6 and layer 18, layer group including layer 8 and layer 20, layer group including layer 10 and layer 22, and layer group including layer 12 and layer 24, such that within a repeating time, layers that are spatially adjacent are not temporally adjacent.
[0062] In one embodiment, such as Figure 4 As shown, when the number of groups simultaneously excited by multiple layers is even, the steps to adjust the preset excitation timing for the target layer group to obtain the target excitation timing include:
[0063] Step 410: Based on the number of groups of simultaneous excitation of multiple layers, determine several target layer groups; the target layer group includes layers with the same temporal sequence that are simultaneously excited.
[0064] Step 420: Adjust the timing of each target layer group according to the preset excitation timing to obtain the target excitation timing; the timing adjustment position of the target layer group is determined based on the timing of the target layer group in the preset excitation timing.
[0065] Specifically, based on the number of simultaneously excited multilayer groups Ns / MB, several target layer groups can be determined. Each target layer group includes a number of simultaneously excited layers with the same temporal sequence. For example, each target layer group may include layers numbered as follows: d Ns / MB-i d Ns / MB*2-i , ..., d Ns-i , where i can be any integer from 0 to Ns / MB / 2–3, meaning the number of target layer groups can be Ns / MB / 2–2. The timing of each target layer group can be adjusted based on a preset excitation timing sequence. For example, the timing of each target layer group can be shifted forward by Tunit*(Ns / MB / 2–2–i) positions to obtain the target excitation timing sequence. In the target excitation timing sequence, the excitation interval between any spatially adjacent layers in the time dimension is at least Tunit*floor(Ns / MB / 2)-1, where Tunit = TR / (Ns / MB) is the excitation acquisition time for each layer group, and floor represents rounding down. By adjusting the target layer groups determined above, sufficient longitudinal relaxation recovery time is ensured between each excited layer and adjacent layers, maximizing the reduction of inter-layer crosstalk.
[0066] In some examples, such as Figure 5 The diagram shows the target excitation timing obtained by adjusting the sequence with Ns=24 and MB=2 as an example. Based on the number of layers simultaneously exciting, the following layer groups can be determined: those including layers 12 and 24, layers 11 and 23, layers 10 and 22, and layers 9 and 21. The time dimension of the layer group including layers 12 and 24 can be shifted forward 4 positions in the preset excitation timing; the time dimension of the layer group including layers 11 and 23 can be shifted forward 3 positions; the time dimension of the layer group including layers 10 and 22 can be shifted forward 2 positions; and the time dimension of the layer group including layers 9 and 21 can be shifted forward 1 position, thus obtaining the target excitation timing. After sorting optimization, the excitation interval for spatially adjacent layers within each repetition time or between adjacent repetition times in the time dimension is at least Tunit*5, which can minimize inter-layer crosstalk.
[0067] In one embodiment, the step of adjusting the timing of each target layer group to obtain the target excitation timing for a preset excitation timing includes:
[0068] Based on the preset excitation timing sequence, the timing sequence of each target layer group is adjusted according to the timing adjustment position based on the preset timing adjustment order to obtain the target excitation timing sequence. In the preset timing adjustment order, the timing adjustment positions of each target layer group are different, and the timing adjustment positions of each target layer group are all less than the preset value. The preset value is determined based on the number of groups that are simultaneously excited in multiple layers.
[0069] Specifically, based on a preset excitation timing sequence, the timing adjustment positions of the target layer groups can be adjusted accordingly. Since the timing of the remaining layer groups will also change after each adjustment of the target layer group's timing, the timing of each target layer group can be adjusted sequentially based on the preset timing adjustment order to obtain the target excitation timing sequence. In the preset timing adjustment order, the timing adjustment position of each target layer group is different. For example, the timing adjustment position of each target layer group can be decreased sequentially to quickly complete the timing adjustment with a small impact range. The timing adjustment position of each target layer group can be less than a preset value determined based on the number of groups simultaneously exciting multiple layers. For example, the preset value can be half of the number of groups simultaneously exciting multiple layers minus one. By adjusting the timing of the target layer group in the above manner, the target excitation timing can be obtained quickly and accurately. By setting the timing adjustment position of each target layer group to be less than the preset value, it can be ensured that the adjusted target excitation timing still satisfies that the timing of each layer with odd number is before the timing of each layer with even number, or the timing of each layer with odd number is after the timing of each layer with even number. At the same time, it avoids that layers that are adjacent in excitation timing after adjustment are also adjacent in space, thereby reducing interlayer crosstalk.
[0070] In some examples, the preset excitation timing can be the timing adjustment order of the target layer group determined by the value of i from smallest to largest. When i = 0, in each repetition time, the excitation timing can include layer d. Ns / MB-i d Ns / MB*2-i , ..., d Ns-i The layer group is shifted forward by Tunit*(Ns / MB / 2–2–i) positions in the time dimension; the value of i is increased by 1. If Ns / MB / 2–2–i = 0, the adjustment ends; if Ns / MB / 2–2–i > 0, the layer d is included. Ns / MB-i d Ns / MB*2-i , ..., d Ns-iThe layer group is shifted forward by Tunit*(Ns / MB / 2–2–i) positions in the time dimension until Ns / MB / 2–2–i=0 is satisfied. Taking Ns=24 and MB=2 as an example, when i=0, it can be determined that the time dimension of the layer group including layer 12 and layer 24 in the preset excitation timing is shifted forward by 4 positions to obtain the timing of the layer in the target excitation timing; when i=1, it can be determined that the time dimension of the layer group including layer 11 and layer 23 in the preset excitation timing is shifted forward by 3 positions to obtain the timing of the layer in the target excitation timing; when i=2, it can be determined that the time dimension of the layer group including layer 10 and layer 22 in the preset excitation timing is shifted forward by 2 positions to obtain the timing of the layer in the target excitation timing; when i=3, it can be determined that the time dimension of the layer group including layer 9 and layer 21 in the preset excitation timing is shifted forward by 1 position to obtain the timing of the layer in the target excitation timing. After sorting optimization, the excitation interval of each spatially adjacent layer within each repetition time or between adjacent repetition times in the time dimension is at least Tunit*5, so that the transition region between each excited layer and the adjacent layer has sufficient longitudinal relaxation recovery time, which can reduce interlayer crosstalk to the greatest extent.
[0071] In one embodiment, the method further includes:
[0072] When the number of groups of multiple layers are simultaneously excited is odd, the target object is subjected to multiple layers of simultaneous excitation processing based on the radio frequency pulse controlled by the preset excitation timing.
[0073] Specifically, when the number of groups of multiple layers excited simultaneously is odd, an alternating excitation and acquisition method of odd and even layers can be adopted. In a relatively long repetition time, the layers with odd spatial positions are excited first in a certain layer group order, and the corresponding magnetic resonance signals are acquired simultaneously. Then, the layers with even spatial positions are excited in a certain layer group order, and the corresponding magnetic resonance signals are acquired simultaneously. Alternatively, the layers with even spatial positions are excited first, and then the layers with odd spatial positions are excited, until all layers are excited, and the corresponding magnetic resonance signals are acquired simultaneously. The numbering can be obtained by sequentially sorting the spatial positions of each imaging layer of the target object. In the preset excitation timing determined by the above-mentioned odd-even layer staggered excitation acquisition method, within a repetition time, the timing of each layer with odd numbers precedes the timing of each layer with even numbers, or the timing of each layer with odd numbers follows the timing of each layer with even numbers, and the excitation timing of each layer is the same in each repetition time; the layers to be excited simultaneously can be determined based on the numerical difference of the layer numbers and the number of groups of multiple layers to be excited simultaneously. The preset excitation timing ensures that the excitation interval between spatially adjacent layers in the time dimension is at least Tunit*floor(Ns / MB / 2). By controlling the radio frequency pulse based on the preset excitation timing when the number of groups of multiple layers to be excited simultaneously is odd, the target object can be processed by multiple layers to be excited simultaneously, which can provide a longitudinal relaxation recovery time of approximately TR / 2 in the transition region between adjacent layers. This ensures that after the signal in the transition region of the adjacent layer is saturated when a certain layer is excited, the saturated transition region has sufficient longitudinal relaxation recovery time, thereby avoiding interlayer crosstalk and improving the acquisition quality of the magnetic resonance signal for the target object.
[0074] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages of other steps.
[0075] Based on the same inventive concept, this application also provides a magnetic resonance signal acquisition device for implementing the magnetic resonance signal acquisition method described above. The solution provided by this device is similar to the implementation described in the above method; therefore, the specific limitations in one or more embodiments of the magnetic resonance signal acquisition device provided below can be found in the limitations of the magnetic resonance signal acquisition method described above, and will not be repeated here.
[0076] In one embodiment, such as Figure 6 As shown, a magnetic resonance signal acquisition device is provided. The device includes:
[0077] The group number acquisition module 610 is used to acquire the number of groups of radio frequency pulses that simultaneously excite multiple layers of the target object;
[0078] The timing adjustment module 620 is used to adjust the preset excitation timing for the target layer group when the number of groups of multiple layers being excited simultaneously is even, so as to obtain the target excitation timing; the target layer group includes the first or last group of layers excited within one repetition time of the radio frequency pulse; in the target excitation timing, spatially adjacent layers are not temporally adjacent.
[0079] The first excitation module 630 is used to perform multi-layer simultaneous excitation processing on the target object based on the target excitation timing control radio frequency pulse;
[0080] The target imaging module 640 is used to acquire multi-layer simultaneous excitation data of the target object; the multi-layer simultaneous excitation data is used to perform magnetic resonance imaging on the target object.
[0081] In one embodiment, the group number acquisition module 610 is further configured to acquire scanning parameters of the target object; the scanning parameters include the number of layers simultaneously excited by radio frequency pulses and the total number of layers of the target object; and the number of groups of multiple layers simultaneously excited is determined based on the number of layers simultaneously excited and the total number of layers.
[0082] In one embodiment, the timing adjustment module 620 is further configured to determine several target layer groups based on the number of groups of multiple layers being simultaneously excited; the target layer group includes several layers with the same timing that are simultaneously excited; the timing of each target layer group is adjusted for a preset excitation timing to obtain a target excitation timing; the timing adjustment position of the target layer group is determined based on the timing of the target layer group in the preset excitation timing.
[0083] In one embodiment, the timing adjustment module 620 is further configured to adjust the timing of each target layer group according to the timing adjustment position based on the preset excitation timing sequence and the preset timing adjustment order to obtain the target excitation timing sequence; in the preset timing adjustment order, the timing adjustment positions of each target layer group are different, and the timing adjustment positions of each target layer group are all less than the preset value; the preset value is a value determined based on the number of groups of multiple layers being excited simultaneously.
[0084] In one embodiment, the device further includes:
[0085] The second excitation module is used to perform multi-layer simultaneous excitation processing on the target object based on the preset excitation timing control radio frequency pulse when the number of groups of multi-layer simultaneous excitation is odd.
[0086] Each module in the aforementioned magnetic resonance signal acquisition device can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in the processor of a computer device in hardware form or independent of it, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.
[0087] In one embodiment, a magnetic resonance scanning system is provided. The system includes a magnetic resonance scanning device and a processing unit connected to the magnetic resonance scanning device; the magnetic resonance scanning device is used to transmit radio frequency pulses to a target object for multi-level simultaneous excitation processing, and to acquire multi-level simultaneous excitation data of the target object; the processing unit stores a computer program, and when the processing unit executes the computer program, it implements the steps of the above-described method.
[0088] In one embodiment, a processing unit is provided, which may be a terminal, and its internal structure diagram may be as follows: Figure 7 As shown, the processing unit includes a processor, memory, input / output interface, communication interface, display unit, and input device. The processor, memory, and input / output interface are connected via a system bus, and the communication interface, display unit, and input device are also connected to the system bus via the input / output interface. The processor provides computational and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The input / output interface is used for exchanging information between the processor and external devices. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, mobile cellular networks, NFC (Near Field Communication), or other technologies. When the computer program is executed by the processor, it implements a magnetic resonance signal acquisition method. The display unit is used to form a visually visible image and can be a display screen, projection device, or virtual reality imaging device. The display screen can be an LCD screen or an e-ink screen. The input device of the processing unit can be a touch layer covering the display screen, or a button, trackball, or touchpad set on the housing of the processing unit, or an external keyboard, touchpad, or mouse, etc.
[0089] Those skilled in the art will understand that Figure 7 The structure shown is merely a block diagram of a portion of the structure related to the present application and does not constitute a limitation on the computer device to which the present application is applied. Specific computer devices may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.
[0090] In one embodiment, a computer-readable storage medium is provided. The computer-readable storage medium stores a computer program thereon, which, when executed by a processor, implements the steps of the method described above.
[0091] In one embodiment, a computer program product is provided. The computer program product includes a computer program that, when executed by a processor, implements the steps of the method described above.
[0092] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium, and when executed, it can include the processes of the embodiments of the above methods. Any references to memory, databases, or other media used in the embodiments provided in this application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. By way of illustration and not limitation, RAM can take many forms, such as Static Random Access Memory (SRAM) or Dynamic Random Access Memory (DRAM). The databases involved in the embodiments provided in this application may include at least one type of relational database and non-relational database. Non-relational databases may include, but are not limited to, blockchain-based distributed databases. The processors involved in the embodiments provided in this application may be general-purpose processors, central processing units, graphics processing units, digital signal processors, programmable logic devices, quantum computing-based data processing logic devices, etc., and are not limited to these.
[0093] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0094] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.
Claims
1. A method for acquiring magnetic resonance signals, characterized in that, The method includes: Obtain the number of groups of radio frequency pulses that simultaneously excite multiple layers of the target object; When the number of groups of multiple layers simultaneously excited is even, the preset excitation timing is adjusted for the target group of layers to obtain the target excitation timing; the target group of layers includes the first or last group of layers excited within one repetition time of the radio frequency pulse; in the target excitation timing, spatially adjacent layers are not temporally adjacent. Based on the target excitation timing control, the radio frequency pulse is used to perform multi-layer simultaneous excitation processing on the target object; Multi-layer simultaneous excitation data of the target object are acquired; the multi-layer simultaneous excitation data is used to perform magnetic resonance imaging on the target object.
2. The method according to claim 1, characterized in that, The step of obtaining the number of groups of radio frequency pulses that simultaneously excite multiple layers of the target object includes: Obtain the scanning parameters of the target object; the scanning parameters include the number of layers simultaneously excited by the radio frequency pulse and the total number of layers of the target object; The number of groups of simultaneous multi-layer excitation is determined based on the number of simultaneously excited layers and the total number of layers.
3. The method according to claim 2, characterized in that, For the preset excitation timing sequence, within one repetition time period, the timing sequence of each layer with odd numbers is before the timing sequence of each layer with even numbers, or the timing sequence of each layer with odd numbers is after the timing sequence of each layer with even numbers; the numbering is obtained by sequentially sorting the spatial positions of each layer of the target object; the numerical difference between the numbers of the layers simultaneously excited in the preset excitation timing sequence is an integer multiple of the number of groups of multiple layers simultaneously excited.
4. The method according to claim 3, characterized in that, The step of adjusting the preset excitation timing for the target layer group to obtain the target excitation timing when the number of simultaneously excited multilayer groups is even includes: Based on the number of simultaneously excited multilayer groups, several target layer groups are determined; the target layer group includes the number of simultaneously excited layers with the same temporal sequence. For the preset excitation timing sequence, the timing sequence of each target layer group is adjusted to obtain the target excitation timing sequence; the timing adjustment position of the target layer group is determined based on the timing sequence of the target layer group in the preset excitation timing sequence.
5. The method according to claim 4, characterized in that, The step of adjusting the timing of each target layer group to obtain the target excitation timing, based on the preset excitation timing, includes: Based on the preset excitation timing sequence, and according to the preset timing adjustment order, the timing sequence of each target layer group is adjusted according to the timing adjustment position to obtain the target excitation timing sequence; in the preset timing adjustment order, the timing adjustment positions of each target layer group are different, and the timing adjustment positions of each target layer group are all less than a preset value; the preset value is a value determined based on the number of groups of multiple layers being excited simultaneously.
6. The method according to claim 1 or 3, characterized in that, The method further includes: When the number of groups of the multi-layer simultaneous excitation is odd, the radio frequency pulse is controlled based on the preset excitation timing to perform the multi-layer simultaneous excitation process on the target object.
7. A magnetic resonance signal acquisition device, characterized in that, The device includes: The group number acquisition module is used to acquire the number of groups of radio frequency pulses that simultaneously excite multiple layers of the target object; The timing adjustment module is used to adjust the preset excitation timing for the target layer group when the number of groups of the multilayers being excited simultaneously is even, so as to obtain the target excitation timing; the target layer group includes the first or last group of layers excited within one repetition time of the radio frequency pulse; in the target excitation timing, spatially adjacent layers are not temporally adjacent. The first excitation module is used to control the radio frequency pulse based on the target excitation timing to perform multi-layer simultaneous excitation processing on the target object; The target imaging module is used to acquire multi-layer simultaneous excitation data of the target object; the multi-layer simultaneous excitation data is used to perform magnetic resonance imaging on the target object.
8. A magnetic resonance scanning system, characterized in that, The system includes a magnetic resonance scanning device and a processing unit connected to the magnetic resonance scanning device; the magnetic resonance scanning device is used to transmit the radio frequency pulse to the target object to perform the multi-layer simultaneous excitation processing, and to acquire the multi-layer simultaneous excitation data of the target object; the processing unit stores a computer program, and when the processing unit executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.
9. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.
10. A computer program product, comprising a computer program, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 6.